Alert archive / Florida / Mesoscale Discussions in 2021

Mesoscale Discussion 1923

October 28, 20219 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Oct 28, 2021, 2:08 PM EDT for 9 counties in Florida. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued
Oct 28, 2021, 2:08 PM EDT (18:08 UTC)
Expired
Oct 28, 2021, 3:45 PM EDT
In force
97 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 545

Counties Charlotte County, FL, DeSoto County, FL, Flagler County, FL, Hardee County, FL, Lake County, FL, Manatee County, FL, Orange County, FL, Polk County, FL, Volusia County, FL

The radar

The Tampa radar (KTBW), 63 km from the middle of the area, began a volume at 18:09 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Tampa Bay, FL (KTBW), launched 12:00Z, 6.1 hours before the alert went out and 63 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Tampa Bay, FL at 12:00Z on 2021-10-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1406 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Tampa Bay, FL at 12:00Z on 2021-10-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 211 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1406 J/kg
Mixed-layer CIN
-14 J/kg
Mixed-layer LCL
675 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
211 m²/s²
0-3 km storm-relative helicity
236 m²/s²
Significant tornado parameter
1.5
Supercell composite
10.9

Open this sounding in Storm Lab

The text

As transmitted.

066 
ACUS11 KWNS 281809
SWOMCD
SPC MCD 281808 
FLZ000-281945-

Mesoscale Discussion 1923
NWS Storm Prediction Center Norman OK
0108 PM CDT Thu Oct 28 2021

Areas affected...central through south central Florida

Concerning...Tornado Watch 545...

Valid 281808Z - 281945Z

The severe weather threat for Tornado Watch 545 continues.

SUMMARY...Threat for isolated damaging wind and a couple of
tornadoes will persist through 21Z across central Florida.

DISCUSSION...A broken line of storms extends from south of
Jacksonville to just south of the Tampa area. Some supercell
structures are evident embedded within and just east of the line.
VWP data from Tampa prior to the arrival of the line show vertical
shear has increased during the past hour with 200-250 m2/s2 storm
relative helicity along with 40-45 kt effective bulk shear. The most
favorable environment for damaging wind and tornadoes will exist
during the next few hours, followed by a decreasing severe threat
after 21Z as low-level winds begin to undergo more substantial
veering.

..Dial.. 10/28/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MFL...MLB...TBW...JAX...

LAT...LON   27398248 28098216 29248164 29698120 28718113 27188141
            26608154 26708216 27398248

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 27, 8:21 PM EDTTornado WatchSPCEscambia, Okaloosa, Santa Rosa7 hr
Oct 27, 10:08 PM EDTMesoscale DiscussionSPCEscambia, Okaloosa, Santa Rosa97 min
Oct 27, 11:22 PM EDTMesoscale DiscussionSPCBay, Franklin, Gulf, Walton2 hr
Oct 28, 12:21 AM EDTTornado WatchSPCBay, Calhoun, Franklin, Gulf, Liberty, Wakulla and 2 more6 hr
Oct 28, 8:12 AM EDTMesoscale DiscussionSPCAlachua, Bradford, Citrus, Dixie, Gilchrist, Hernando and 7 more2 hr
Oct 28, 9:00 AM EDTTornado WatchSPCAlachua, Baker, Bradford, Brevard, Charlotte, Citrus and 35 more10 hr
Oct 28, 11:51 AM EDTMesoscale DiscussionSPCCharlotte, DeSoto, Flagler, Hardee, Highlands, Hillsborough and 11 more114 min
Oct 28, 4:11 PM EDTMesoscale DiscussionSPCBrevard, Charlotte, DeSoto, Glades, Highlands, Indian River and 2 more94 min

Nearby

Mesoscale Discussions in Florida, 2021Every mesoscale discussion in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.